jdk动态代理简介说明

jdk动态代理简介

jdk动态代理:
     使用反射机制
	 当代码运行时动态生成代理类.class文件
我们将这种运行时的代理类称之为"jdk动态代理"

接口

package com.java265.dynamic;
public interface Target {
   public String execute();
}

实现类
package com.java265.dynamic;
public class TargetImpl implements Target {
   @Override
   public String execute() {
       System.out.println("TargetImpl execute！");
       return "execute";
  }
}

代理类
package com.java265.dynamic;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
public class DynamicProxyHandler implements InvocationHandler{
   private Target target;
   public DynamicProxyHandler(Target target) {
       this.target = target;
  }

   @Override
   public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
       System.out.println("========before==========");
       Object result = method.invoke(target,args);
       System.out.println("========after===========");
       return result;
  }
}


测试类
package com.java265.dynamic;
import java.lang.reflect.Proxy;
public class DynamicProxyTest {
    public static void main(String[] args) {
        Target target = new TargetImpl();
        DynamicProxyHandler handler = new DynamicProxyHandler(target);
        Target proxySubject = (Target) Proxy.newProxyInstance(TargetImpl.class.getClassLoader(),TargetImpl.class.getInterfaces(),handler);
        String result = proxySubject.execute();
        System.out.println(result);
    }
}

-----运行以上代码，将输出以下信息-----
========before==========
TargetImpl execute！
========after===========
execute

注意事项:
      jdk动态代理和静态代理都编写定义接口,然后才能实现代理功能
	  因为她们都利用了(java代码的多态性)实现运行时绑定效果